My one year old frenchie has diarrhea with blood

[Cathduque]

Hello, I have a one year old male Frenchie and I got him 4 weeks ago. He came with diarrhea with blood. Went to vet already 3 times, blood test ok, stool test ok, they change his food, gave antibiotics twice and still with diarrhea with blood. He eats well, play, etc. I don't know what to do anymore. Can somebody also recomend a good pet insurance and a good vet specialized in dog gastroenterology in Miami. Thanks.